Citrus fruits have long been recognized as valuable sources of important nutrients. More recently, health benefits and disease retarding or treating benefits of citrus sources have come to be more fully recognized as advantageous and beneficial when ingested. Accordingly, there is a general belief that increasing the intake of citrus-originating foods is a beneficial and important objective in the overall scheme of human health.
One potential source of citrus juice solids is the large volume of citrus peel material which traditionally has been used in low value applications such as livestock feed. Many tons of citrus peel material are collected as byproduct each citrus harvesting season when juice is extracted from whole citrus fruit by commercial extraction equipment from FMC Corporation, Brown AME and others. Such citrus fruits including orange, grapefruit, tangerine and lemon fruits. In terms of volume of juice extracted and citrus peel byproduct material collected, orange-originating products present both the greatest challenge for higher value use and the most promising potential for economic advantage. Heretofore, these peel material resources have been underutilized due to negative characteristics of peels, which characteristics can be considered objectionable on a very wide scale.
Certain approaches have been taken in the past in an effort to process citrus extraction peel byproduct material into products which have a value that is high than use as livestock feed. Once such approach is that of Bonnell U.S. Pat. No. 4,497,838. This shows a process for recovering “useful” products from orange peels through use of a countercurrent solvent extraction that is carried out with a non-aqueous solvent such as an alcohol. An aqueous extract is collected which contains most of the sugars, essential oils and bioflavanoids from the citrus peel byproduct. A sugar syrup product is said to be produced, as well as an “orange flower” solid product which in high in cellulose and pectin.
Other approaches, such as shown in U.S. Pat. No. Re. 22,865 and No. 2,215,944 (Boscawen), set forth a process in which water is added to ground peel and the resulting mixture is passed through a press. While a press liquor is recovered, the peel is subjected to hydroxy treatment to form a gel, which is treated with an acid in order to form pulpy solids. These are separated in order to collect the solids for the food product of these patents. The focus of this product is use as animal feed.
Other peel extraction approaches have been suggested. Eschinasi U.S. Pat. No. 4,016,351 shows extracting juice from peel by adding water and calcium to peel prior to pressing the peel in order to form a press cake that is the product of this patent. Calcium is removed with an oxalic acid solution. Gerow U.S. Pat. No. 4,313,372 shows wet pulp/peel being mixed with dilute press liquor and pressed to limit additional press liquor. The wet peel is treated with super heated steam, the material is mixed with lime, and the press cake is dried for collection.
Prior suggested approaches such as these tend to emphasize solvent extraction to form derivative products. Such products are not of a nature to be considered as a citrus juice in its own right. They do not truly recover additional levels of valuable sugar and nutrient sources from byproduct destined for low-grade livestock feed and transform same into a juice product suitable for human consumption. There is accordingly a need for approaches which allow a more complete realization of the potential of citrus fruits, and especially of peel byproduct from citrus fruit juice extraction.
While membrane filtration approaches are generally known for operating upon citrus juice sources with a view toward preparing a variety of different products and byproducts, these approaches typically do not substantially change the characteristics of a citrus peel juice.
In addition, removal of components from citrus sources through the use of an ion exchange resin is generally known and used in debittering or deacidifing traditional citrus juice sources. For example, Mitchell et al. U.S. Pat. No. 4,514,427 notes that bitter narigin and limonin can be removed from citrus juices by contacting the juice with a weak base anionic exchange resin having a matrix of a styrene polymer and functional groups derived from a monoamine or a polyamine. Puri U.S. Pat. No. 4,439,458 describes reducing flavonoid and/or limonoid induced bitterness in citrus fruit juices through adsorption of such bitterness componets by a resin. This patent notes that naringin is a typical flavonoid, that limonin is a typical limonoid, and that the resin can be a styrene divinylbenzene cross-linked co-polymer. Norman et al. U.S. Pat. No. 4,965,083 has a general teaching along these lines, and this patent discloses a post-crosslinked adsorbent resin.
Divinylbenzene adsorptive resins are disclosed in Meitzner et al. U.S. Pat. No. 4,297,220, in Ifuku et al. U.S. Pat. No. 5,734,046, and in Takayanagi et al. U.S. Pat. No. 5,885,638. Mozaffar et al. U.S. Pat. No. 5,817,354 specifically teaches the use of Rohm and Haas AMBERLITE® XAD-16 styrene divinylbenzene resin to adsorb, and thus remove from citrus juices, bitterness compounds such as limonoids, including limonin, nomilin and other compounds, and flavonoids such as narigin and hesperidin. In general, the art recognizes that adsorptive resins such as AMBERLITE® XAD-16 of Rohm and Haas are useful for removing flavonoids and limonoids from citrus juices.
The subject matter of each patent or publication mentioned herein is incorporated by reference hereinto. For example, the chemical structure of the styrene divinylbenzene resins is disclosed in the thus incorporated patented or published subject matter.
As noted generally herein, historically citrus fruit peel byproduct is not used in a high value manner, and many valuable nutrients are not put to use in a manner which directly benefits people. There is accordingly a need for approaches which allow a more complete realization of the potential of citrus fruit peel components. The present invention addresses this need by combining peel Brix and nutrient extraction with microfiltration and debittering so as to provide a peel-originating citrus juice having sensory properties suitable for human use.
Fruit juices of interest include those for use in juice products which are concentrated and which can be reconstituted before distribution to the consumer or thereafter. These so-called “from-concentrate” juices undergo an evaporation or concentration procedure. The invention also is of value for use in providing citrus juices which are consumed without ever being concentrated or subjected to an evaporation process. These can be referred to as “not-from-concentrate” citrus juices.
The juice products which can be prepared according to the invention include filler juices as well as stand-alone juices. Many blended juice products are currently marketed. Most such products include as a primary component what has come to be known as “filler” juice. A filler juice is a relatively inexpensive juice source which is suitable for blending with other juices or juice flavors. Primary filler juices have been apple juice and/or grape juice, particularly white grape juice. These traditional types of filler juices are generally considerably lower in nutritional content than are the peel-originating citrus juices according to the invention. The use of citrus sources as filler juices has developed by technology such as in U.S. Pat. No. 6,054,168. Ideal filler juices are relatively low in cost and have a relatively bland flavor.
Accordingly, there is a need for citrus juices originating from peel byproduct sources which are themselves improved by removing naturally present components which have negative effects on juice products as processed and/or after packaging and storage, while making nutrients and Brix solids available in a form very suitable for human consumption.